2011901821 has 2 divisors, whose sum is σ = 2011901822. Its totient is φ = 2011901820.

The previous prime is 2011901813. The next prime is 2011901851. The reversal of 2011901821 is 1281091102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1070271225 + 941630596 = 32715^2 + 30686^2 .

It is a cyclic number.

It is not a de Polignac number, because 2011901821 - 2³ = 2011901813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2011901851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1005950910 + 1005950911.

It is an arithmetic number, because the mean of its divisors is an integer number (1005950911).

Almost surely, 2^2011901821 is an apocalyptic number.

It is an amenable number.

2011901821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2011901821 is an equidigital number, since it uses as much as digits as its factorization.

2011901821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 25.

The square root of 2011901821 is about 44854.2285743496. The cubic root of 2011901821 is about 1262.4153344654.

Adding to 2011901821 its reverse (1281091102), we get a palindrome (3292992923).

The spelling of 2011901821 in words is "two billion, eleven million, nine hundred one thousand, eight hundred twenty-one".